National Institute for Public Health and the Environment, Bilthoven, The Netherlands.
BMJ Open. 2013 Aug 29;3(8):e002933. doi: 10.1136/bmjopen-2013-002933.
Idiopathic Environmental Intolerance (IEI) attributed to electromagnetic fields (EMF) refers to self-reported sensitivity mainly characterised by the attribution of non-specific physical symptoms to low-level EMF exposure emitted from sources such as mobile phones. Scientific studies have not provided evidence for the existence of IEI-EMF, but these studies did not resemble the real-life situation or suffered from poor exposure characterisation and biased recall of health symptoms. To improve existing methods for the study of IEI-EMF, an Ecological Momentary Assessment (EMA) study is designed.
The study is an EMA study in which respondents carry personal exposure metres (exposimeters) that measure radiofrequency (RF) EMF, with frequent assessment of health symptoms and perceived EMF exposure through electronic diary registration during five consecutive days. Participants will be a selection from an epidemiological study who report to be sensitive to RF EMF. The exposimeters measure electric field strength in 12 frequency bands. Diary questions include the occurrence and severity of 10 non-specific physical symptoms, mood states and perceived exposure to (sources of) EMF. The relationship of actual and perceived EMF exposure and mood with non-specific physical symptoms will be analysed using multilevel regression analysis with time-shift models.
The study has several advantages over previous studies, including assessment of personal EMF exposure and non-specific physical symptoms by an ecological method with a minimised chance of recall bias. The within-person design reduces confounding by time-stable factors (eg, personal characteristics). In the conduct of the study and the analysis and interpretation of its outcomes, some methodological issues including a high participant burden, reactivity, compliance to the study protocol and the potential of chance findings due to multiple statistical testing will be accounted for and limited as much as possible.
归因于电磁场（EMF）的特发性环境敏感（IEI）是指自我报告的敏感性，主要表现为将非特异性身体症状归因于低水平 EMF 暴露，这些暴露源可能来自手机等。科学研究并未提供 IEI-EMF 存在的证据，但这些研究与现实生活情况不符，或者暴露特征描述不佳，对健康症状的回忆存在偏差。为了改进研究 IEI-EMF 的现有方法，设计了一项生态瞬时评估（EMA）研究。
该研究是一项 EMA 研究，其中受访者携带个人暴露计（暴露计），可测量射频（RF）EMF，并通过电子日记登记在连续五天内频繁评估健康症状和感知的 EMF 暴露情况。参与者将从报告对 RF EMF 敏感的流行病学研究中选择。暴露计测量 12 个频带的电场强度。日记问题包括 10 种非特异性身体症状的发生和严重程度、情绪状态以及对（EMF）源的感知暴露。将使用具有时间偏移模型的多层次回归分析来分析实际和感知的 EMF 暴露与非特异性身体症状之间的关系。
该研究与之前的研究相比具有几个优势，包括通过生态方法评估个人 EMF 暴露和非特异性身体症状，并且最小化了回忆偏差的可能性。个体内设计减少了时间稳定因素（例如，个体特征）的混杂。在研究的进行、分析和结果解释中，将考虑并尽可能限制一些方法学问题，包括参与者负担过重、反应性、对研究方案的依从性以及由于多次统计检验而导致偶然发现的可能性。
